linux/sound/soc/codecs/rl6231.c

/*
 * rl6231.c - RL6231 class device shared support
 *
 * Copyright 2014 Realtek Semiconductor Corp.
 *
 * Author: Oder Chiou <oder_chiou@realtek.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>

#include "rl6231.h"

/**
 * rl6231_calc_dmic_clk - Calculate the parameter of dmic.
 *
 * @rate: base clock rate.
 *
 * Choose dmic clock between 1MHz and 3MHz.
 * It is better for clock to approximate 3MHz.
 */
int rl6231_calc_dmic_clk(int rate)
{
	int div[] = {2, 3, 4, 6, 8, 12}, idx = -EINVAL;
	int i, red, bound, temp;

	red = 3000000 * 12;
	for (i = 0; i < ARRAY_SIZE(div); i++) {
		bound = div[i] * 3000000;
		if (rate > bound)
			continue;
		temp = bound - rate;
		if (temp < red) {
			red = temp;
			idx = i;
		}
	}

	return idx;
}
EXPORT_SYMBOL_GPL(rl6231_calc_dmic_clk);

/**
 * rl6231_pll_calc - Calcualte PLL M/N/K code.
 * @freq_in: external clock provided to codec.
 * @freq_out: target clock which codec works on.
 * @pll_code: Pointer to structure with M, N, K and bypass flag.
 *
 * Calcualte M/N/K code to configure PLL for codec.
 *
 * Returns 0 for success or negative error code.
 */
int rl6231_pll_calc(const unsigned int freq_in,
	const unsigned int freq_out, struct rl6231_pll_code *pll_code)
{
	int max_n = RL6231_PLL_N_MAX, max_m = RL6231_PLL_M_MAX;
	int k, red, n_t, pll_out, in_t, out_t;
	int n = 0, m = 0, m_t = 0;
	int red_t = abs(freq_out - freq_in);
	bool bypass = false;

	if (RL6231_PLL_INP_MAX < freq_in || RL6231_PLL_INP_MIN > freq_in)
		return -EINVAL;

	k = 100000000 / freq_out - 2;
	if (k > RL6231_PLL_K_MAX)
		k = RL6231_PLL_K_MAX;
	for (n_t = 0; n_t <= max_n; n_t++) {
		in_t = freq_in / (k + 2);
		pll_out = freq_out / (n_t + 2);
		if (in_t < 0)
			continue;
		if (in_t == pll_out) {
			bypass = true;
			n = n_t;
			goto code_find;
		}
		red = abs(in_t - pll_out);
		if (red < red_t) {
			bypass = true;
			n = n_t;
			m = m_t;
			if (red == 0)
				goto code_find;
			red_t = red;
		}
		for (m_t = 0; m_t <= max_m; m_t++) {
			out_t = in_t / (m_t + 2);
			red = abs(out_t - pll_out);
			if (red < red_t) {
				bypass = false;
				n = n_t;
				m = m_t;
				if (red == 0)
					goto code_find;
				red_t = red;
			}
		}
	}
	pr_debug("Only get approximation about PLL\n");

code_find:

	pll_code->m_bp = bypass;
	pll_code->m_code = m;
	pll_code->n_code = n;
	pll_code->k_code = k;
	return 0;
}
EXPORT_SYMBOL_GPL(rl6231_pll_calc);

int rl6231_get_clk_info(int sclk, int rate)
{
	int i, pd[] = {1, 2, 3, 4, 6, 8, 12, 16};

	if (sclk <= 0 || rate <= 0)
		return -EINVAL;

	rate = rate << 8;
	for (i = 0; i < ARRAY_SIZE(pd); i++)
		if (sclk == rate * pd[i])
			return i;

	return -EINVAL;
}
EXPORT_SYMBOL_GPL(rl6231_get_clk_info);

MODULE_DESCRIPTION("RL6231 class device shared support");
MODULE_AUTHOR("Oder Chiou <oder_chiou@realtek.com>");
MODULE_LICENSE("GPL v2");